Extreme Temperature Diary- Monday May 11th, 2020/ Main Topic: Hotter Than Average Temperatures Ahead Across Most of the U.S. For Late May

Monday May 11th… Dear Diary. The main purpose of this ongoing blog will be to track United States extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉

Main Topic: Hotter Than Average Temperatures Ahead Across Most of the U.S. For Late May

Dear Diary. Over Mother’s Day weekend meteorological models became very consistent, forecasting a big warming trend starting this week for the U.S. to the east of the coastal West states. Yep, due to climate change we can’t expect eye opening record breaking cold weather in the East to stick around too long…plus it’s mid May anyway, so it will get warm. As of May 11th people are complaining chilly winter-like conditions hanging on from the Midwest through the Northeast. In ten days many will be complaining about the heat.

In just a few days we will see our old nemesis, the heat dome, popping up across the mid section of the country:

I did see this Twitter note:

All kidding aside, here is a good write from my friend Matthew Cappucci from the Washington Post on the upcoming toasty weather pattern with some stormy ramifications:


apital Weather Gang

A sudden pattern change will dramatically heat up the East and cool down the West by the weekend

After record cold and snow in the East, a dose of late spring and summer is coming

A look at the upcoming weather pattern with warmth in the East and a cool-down in the West. Meanwhile, active weather can be expected across the nation’s heartland. (WeatherBell) By Matthew Cappucci May 11 at 12:48 PM

After a weeks-long stretch of chilly weather in the East and scorching warmth across the West, the stubborn pattern dominating the nation’s weather is just days away from easing its harsh grip on the country. A dramatic warm-up is in store for cold-weary residents in the Northeast, where temperatures up to 30 degrees below normal and even snow made the start of May feel more like March.

[A historic blast of the polar vortex set scores of records and scattered rare May snow in Eastern U.S.]

Meanwhile, the unbearable heat sizzling the Southwest has begun to ease. Monday could be the first day in a week that Phoenix doesn’t hit 100 degrees, a welcome relief from the brutal scorcher that has brought summertime temperatures a month ahead of schedule.

The dramatic changes come as a weather pattern shift teeters the United States’ meteorological seesaw in the other direction. It’s set to shuffle the obstinately stagnant air masses, but it could also favor a flurry of active weather in the nation’s heartland.

A nation divided

A look at the dominant weather pattern that started May 2020 over the Lower 48. Shadings denote temperature anomalies during the period. (WeatherBell)

Mother’s Day felt more like St. Patrick’s Day along the Eastern Seaboard, where a piece of the tropospheric polar vortex pinched south and unleashed a frigid late-season chill. Boston’s Logan International Airport saw a trace of snow on Saturday, its second-latest in the season on record. Central Park in New York City picked up its latest snow ever recorded, with data dating to 1870.

Flakes even flew near the nation’s capital, while a dusting was observed in the high terrain of the Carolinas and eastern Tennessee. Frost made it all the way down to Georgia. The cold at upper levels shattered all-time monthly records in places such as Albany and Buffalo in New York.

[The demise of the polar vortex was expected to spell weather surprises this spring]

At the same time, the Desert Southwest is racking up record highs. Las Vegas matched its warmest April temperature ever recorded (99 degrees), with Phoenix hitting the century mark on 12 of the past 15 days.

That’s all about to change as the serpentine jet stream contorts and morphs its shape, allowing high-altitude cold to spill south over the western half of the country while a dome of warmth swells over the East. It’s a reversal of the teeter-totter that has dominated the Lower 48’s weather as of late. But the swapping air mass brings a chance of severe storms and flooding for some.

A change on the way

Building high pressure in the East should bring near- or above-average temperatures for much of mid- to late May. (WeatherBell)

The upcoming pattern change is all thanks to the orientation of the jet stream. The swiftly moving current of air in the upper atmosphere acts as the boundary between warm air to the south and chilly air banked up north. Meanderings of the jet stream allow subsequent northerly or southerly jaunts of air masses. That’s a key ingredient in the upcoming forecast.

Tuesday into Wednesday, the jet stream will surge north over the eastern United States, allowing a “ridge” of high pressure to build in. A look at long-range data suggests this dome of high pressure will stick around for a while in some capacity. That portends a welcome warm-up, with highs returning to near or above seasonal norms by the end of the week from the Midwest and Ohio Valley to New England.

By late May, many locations east of the Mississippi River may well be enjoying a prolonged stretch of warm, summery weather.

Meanwhile, cold air at the upper levels will tumble south over the West, favoring slightly cooler temperatures for perhaps the remainder of May. Phoenix, which has seen an extended stretch of 100-plus-degree days, is unlikely to hit the triple digits for quite some time. That will result “in noticeably cooler temperatures over the next few days,” wrote the National Weather Service in Phoenix.

An increase in gusty winds is possible over the Desert Southwest, while an uptick in rain activity and cloudiness is on tap for the Pacific Northwest.

A meteorological battleground over the central United States

Clouds hover low to the ground west of Linwood, Kan., on May 28, 2019, shortly before a rain-wrapped EF4 tornado touches down. (Matthew Cappucci)

Where the flip-flopping air masses meet, strong to severe thunderstorms are likely. It has been a quiet few weeks over the Plains; Kansas is nearing third place for its latest first tornado on record.

According to Weather Channel meteorologist Greg Diamond, tornado reports across the country this May are running at about 10 percent of the long-term average. The shockingly slow May comes on the heels of the second-most-active April on record.

The upcoming pattern change is likely to put an end to that as severe weather erupts over traditional Tornado Alley.

Warmth from the southeast will encroach over the Southern Plains, increasing the amount of instability — or “juice” — for storms to feed off. At the same time, periodic turrets of cold from the jet stream’s upper-level dip in the West will energize and trigger repeated rounds of storms.

The first episode is slated for Wednesday, when strong to severe thunderstorms are anticipated west of the Interstate 35 corridor in Oklahoma, parts of north-central Texas near the Red River, and southwest Kansas. Tornadoes are possible.

Farther to the east, heavy rains and flooding are probable when each day’s storms merge and rain themselves out downwind.

Each day this week after Wednesday will feature some chance of severe weather before a brief period of calm to start next week.

[Severe weather outlook for May features a backloaded month for tornadoes]

Matthew Cappucci Matthew Cappucci is a meteorologist for Capital Weather Gang. He earned a B.A. in atmospheric sciences from Harvard University in 2019, and has contributed to The Washington Post since he was 18. He is an avid storm chaser and adventurer, and covers all types of weather, climate science, and astronomy. Follow


I suspect that when May is done there will be a well above average number of record reports, both cold and warm, going into the NCEI record count system. I’ll keep all of my readers informed as to how many and if cold will trump heat or vice a versa.

For now:

Now here are some of today’s articles and notes on the horrid COVID-19 pandemic:

(As usual, the most noteworthy items will be listed first.)

Here is more climate and weather news from Monday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)

Here are some very chilly “ET” reports and some warm readings from Alaska:

(If you like these posts and my work please contribute via the PayPal widget, which has recently been added to this site. Thanks in advance for any support.) 

Guy Walton “The Climate Guy”

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